FdUMP triethylammonium is the intracellular active form of 5-fluorouracil (5-FU). 5-FU is converted to FdUMP after being transported into the cell by various enzymes. FdUMP forms a ternary complex with thymidylate synthase and its cofactor 5,10-methylene tetrahydrofolate, inhibiting the activity of thymidylate synthase, which in turn leads to the suppression of DNA synthesis.
